1. Field
This invention relates to a method and apparatus for in-place repair of a worn pipe section, which clamps the worn section coaxially and longitudinally in place and, while retaining this clamped position, permits the operator to cut free the section, rotate the section to displace the worn part, and subsequently reweld the rotated section to the remainder of the pipe.
2. The Prior Art
Methods and apparatus for positioning and clamping pipe sections in abutting relation for the purpose of welding the ends of the pipe sections together are known. A typical example is revealed in U.S. Pat. No. 3,920,171 issued to Edward A. Clavin as comprising a pipe alignment clamp inserted in one pipe and having gripping shoes at its forward end that may be set in a second pipe, together with means to cause the pipe ends to advance and align so as to form a properly spaced gap for welding the pipe ends together. This apparatus, being operative from inside of the pipe, is impossible to use outside of the pipe as in the present invention to repair an already connected but unduly worn pipe section.
Another example of the prior art is shown in U.S. Pat. No. 3,658,231 issued to Bruce Calvin Gilman. This patent discloses a complex structure useable at the sea bottom to weld pipeline strings together. Such patent contains a welding chamber into which the pipe ends are inserted, aligned and advanced by hydraulic or pneumatic means to form a welding gap, while further means are provided to purge sea water from the welding chamber. The disclosed apparatus is far too complex and cumbersome to be useful for applicant's purpose and would necessitate moving the cut pipe section out of place to assemble in the patented structure. Furthermore, the patented apparatus can be used for welding only one pipe joint at a time, while applicant requires clamps that retain two pipe joints or connections in place.
U.S. Pat. No. 3,422,519, issued Jan. 21, 1969, to Barry F. Fehlman, discloses a welding clamp used to align abutting portions of pipe ends for welding and which has some similarity to applicant's clamp structure in that it provides longitudinally displaced sleeves which are fastened on opposite sides of a pipe joint and are carried by a cage of longitudinal bar members to permit welding of the joint. The patented structure does not permit one pipe to rotate with respect to the other once the clamp is fastened as is necessary in applicant's clamp, nor does the patentee disclose the concept of repairing a worn pipe section by holding it in place with clamp structure which permits the section to be rotated and then rewelded.